1. Technical Field
The present invention relates generally to an automatic electronic parts mounting apparatus, and more particularly to a compact and high-speed electronic parts mounting apparatus designed to mount chip components on a printed circuit board.
2. Background of Related Art
Japanese Patent First Publication No. 6-85492 teaches a robot-operated mounting apparatus, as shown in FIG. 26, which is in widespread use. This mounting apparatus includes an electronic parts feeder 70, a board holder 79 for holding a printed board 75, a mounting head 72, a first drive shaft 73, and a second drive shaft 74. The electronic parts feeder 70 has disposed thereon cassettes 77 for supplying taped electronic parts in sequence. The mounting head 72 supports a pick-up nozzle 71 rotatably and slidably for picking up the electronic parts and mounting them on the printed board 75. The first drive shaft 73 has disposed thereon the mounting head 72. The second drive shaft 74 moves the first drive shaft 73 in a direction perpendicular to the first drive shaft 73 for allowing the mounting head 72 to be displaced in X-and Y-coordinate directions.
Japanese Patent First Publication No. 7-202491 teaches a high-speed rotary mounting apparatus, as shown in FIG. 27, which includes a rotary head 81, a parts feeder 80, an electronic parts monitor 86, and an XY table 83. The rotary head 81 has pick-up nozzles 82 disposed on a circumferential portion thereof which are rotated intermittently. The parts feeder 80 is moved to a location where one of the pick-up nozzles 82 is stopped. The XY table 83 holds a printed board on which electronic parts are to be mounted and moves in two directions perpendicular to each other. The picking up, monitoring, and mounting the electronic parts are achieved in synchronization with rotation of the rotary head 81.
The above prior art mounting apparatuses, however, have the following drawbacks. The robot-operated mounting apparatus is simple and compact in structure, but it is difficult to perform a high-speed operation because the electronic parts are picked up and mounted, one by one, on the printed board 75. The high-speed rotary mounting apparatus can install the electronic parts on the printed board at high speeds, but its structure is bulky, and the cost of equipment is high. A compact and high-speed mounting machine combining the advantages of the above two conventional apparatuses is thus sought.
It is therefore a principal object of the present invention to avoid the disadvantages of the prior art.
It is another object of the present invention to provide a compact and high-speed electronic parts mounting apparatus.
According to one aspect of the present invention, there is provided an electronic parts mounting apparatus which comprises: (a) a first parts feeder including a plurality of cassettes each of which stores therein electronic parts and has a pick-up station; (b) a second parts feeder including a plurality of cassettes each of which stores therein electronic parts and has a pick-up station, the second parts feeder being arranged at a preselected interval away from the first parts feeder in a first direction; (c) a table for holding thereon a printed board on which the electronic parts are to be mounted, the table being disposed within the preselected interval between the first and second parts feeders and designed to move in a second direction perpendicular to the first direction; (d) a first mounting head including a plurality of pick-up nozzles movable in a vertical direction for picking up the electronic parts from the pick-up stations, the first mounting head being disposed so as to move in the first direction; (e) a second mounting head including a plurality of pick-up nozzles movable in the vertical direction for picking up the electronic parts from the pick-up stations, the second mounting head being disposed so as to move in the first direction; and (f) a controller for controlling movement of the table and the first and second mounting heads so that the first and second mounting heads pick up the electronic parts from the pick-up stations and then mount the electronic parts on given places of the printed board held on the table.
In the preferred mode of the invention, the cassettes of each of the first and second parts feeders are disposed adjacent to each other at first pitches in the first direction. The pick-up nozzles of each of the first and second mounting heads are disposed adjacent to each other at second pitches equal to the first pitches.
The controller controls the movement of the first and second mounting heads in first and second operation modes. The first operation mode is such that the first mounting head picks up the electronic parts from the pick-up stations of the first parts feeder through the pick-up nozzles, while the second mounting head mounts the electronic parts which have already been picked up by the pick-up nozzles thereof on the printed board held on the table. The second operation mode is such that the second mounting head picks up the electronic parts from the pick-up stations of the second parts feeder through the pick-up nozzles, while the first mounting head mounts the electronic parts which have already been picked up by the pick-up nozzles thereof on the printed board held on the table.
The controller controls vertical movement of the pick-up nozzles of each of the first and second mounting heads so that the pick-up nozzles of each of the first and second mounting heads pick up the electronic parts simultaneously.
The controller may alternatively control the first and second mounting heads so that a first group consisting of a first number of the pick-up nozzles and a second group consisting of a second number of the pick-up nozzles of each of the first and second mounting heads are moved with different timings for picking up the electronic parts.
Each of the pick-up nozzles of the first group of each of the first and second mounting heads picks up one of the electronic parts from selected one of the pick-up stations of the cassettes in a first pick-up operation, while each of the pick-up nozzles of the second group of each of the first and second mounting heads picks up one of the electronic parts from selected one of the pick-up stations of the cassettes in a second pick-up operation following the first pick-up operation.
The controller may control the vertical movement of the pick-up nozzles of each of the first and second mounting heads so that at least one of the pick-up nozzles of each of the first and second mounting heads is moved to pick up one of the electronic parts from selected one of the pick-up stations of the cassettes.
The controller may control the movement of each of the first and second mounting heads in the first direction and the vertical movement of the pick-up nozzles of each of the first and second mounting heads so that each of a given number of the pick-up nozzles of each of the first and second mounting heads picks up one of the electronic parts from selected one of the pick-up stations of the cassettes.
Each of the first and second mounting heads includes a nozzle-moving mechanism having an elevation member for elevating the pick-up nozzles upward simultaneously and dropping means for dropping the pick-up nozzles independently of each other.
A first and a second sensor are disposed in the first and second parts feeders, respectively, for monitoring the presence and orientation of the electronic parts picked up by the pick-up nozzles and providing signals indicative thereof.
A turning means is further provided which turns each of the pick-up nozzles about the center thereof.
Each of the pick-up nozzles has a length extending in the vertical direction. The turning means turns each of the pick-up nozzles about a center line thereof extending in a lengthwise direction of each of the pick-up nozzles.
A position monitor and a positional shift correcting mechanism are further provided. The position monitor monitors the position of each of the electronic parts held by the pick-up nozzles to determine a positional shift from a given correct position. The positional shift correcting mechanism adjusts a relative position between the table and one of the electronic parts having the positional shift so as to compensate for the positional shift.
The positional shift correcting mechanism includes the turning means and a moving mechanism designed to move the table in the second direction.
The positional shift correcting mechanism also includes a second moving mechanism designed to move the first and second mounting heads in the first direction.